Is there ever a time when repentance is not possible?

[deut31:12]

At some level this is a mystery, something that is not answered in scripture. We were at one point all dead in trespasses and sins with a reprobate mind and so forth, the only reason we have faith is that the Holy Spirit came to us, we did not choose it, we did and do not have that power. So then we do some people run away from the grace when it is offered and they know it is offered?

Scripture says maybe they love the dark more than the light, maybe this is an indicator? I don't know; though we can do great harm by writing people off, when in reality it may only be a couple of more years or hours; and they do a 180 in their faith.

Of course all sin is forgivable and God wills that all men come to repentance, but a reprobate mind is one that is rejected; condemned; disapproved.

There does come a time in our lives where our minds can be seared with a hot iron and/or minds reprobate to where we cannot repent anymore. With the flesh we serve sin and with the mind the will of God. If our consciences are seared and our minds are reprobate they can no longer serve God.

To understand what it is to "Blaspheme the Holy Spirit" go back to see why Jesus made that statement.

But he that shall blaspheme against the Holy Ghost hath never forgiveness, but is in danger of eternal damnation: Because they said, He hath an unclean spirit. - Mark 3:29-30

This is your answer. They accused Jesus of having an unclean spirit when it was through the Holy Spirit that Jesus did these miracles. We cannot blaspheme against the Holy Spirit today because Jesus is not walking the earth today doing miracles.